Prototype Richese No-Fields on foreign Homeworlds

game/homeworld-alliance.ts

@@ -1,4 +1,7 @@
-import { homeworldForceGroups, type HomeworldCustody, type HomeworldCustodyContext } from './homeworld-custody';
+import { HomeworldCustodyError, homeworldForceGroups, type HomeworldCustody, type HomeworldCustodyContext } from './homeworld-custody';
+
+/** Public marker presence only; token identity and denomination are private. */
+export type HomeworldAllianceMarker = { homeworld: string; controller: string };
 
 /** E3 alliance restriction uses present foreign forces, independently of any
  * saved turn entitlement to an occupied card's benefits. */
@@ -7,8 +10,19 @@ export function homeworldAllianceBlock(
   custody: HomeworldCustody,
   first: string,
   second: string,
+  marker?: HomeworldAllianceMarker | null,
 ): string | null {
-  const occupied = homeworldForceGroups(context, custody).some((world) => {
+  const worlds = homeworldForceGroups(context, custody);
+  if (marker) {
+    const world = worlds.find(row => row.id === marker.homeworld);
+    const controller = context.players.find(row => row.id === marker.controller);
+    if (!world || !controller || controller.faction !== 'richese' || world.native === controller.id)
+      throw new HomeworldCustodyError('Homeworld alliance marker needs its seated Richese controller and an active foreign world.');
+    if ((world.native === first && controller.id === second) ||
+        (world.native === second && controller.id === first))
+      return 'An alliance cannot form while either faction has forces on the other’s Homeworld.';
+  }
+  const occupied = worlds.some((world) => {
     const visitor = world.native === first ? second : world.native === second ? first : null;
     const forces = visitor ? world.forces[visitor] : undefined;
     return !!forces && forces.normal + forces.elite > 0;